An anonymous reader writes: Data science — or "big data" if you prefer — has evolved into a full-fledged buzzword, thanks to marketing departments around the world. John Foreman writes that part of the marketing blitz has been focused on how fast big data analysis can be. Most companies offering some kind of analytic service try to sell you on how it'll make it easy for you to quickly find and fix the problems with your business. But he points out that good, robust models need a stable set of inputs, and businesses often change far too quickly for any kind of stable prediction. He takes IBM's analytic services as an example, quoting Kevin Hillstrom: "If IBM Watson can find hidden correlations that help your business, then why can't IBM Watson stem a 3 year sales drop at IBM?" Foreman offers some simple advice: "Simple analyses don't require huge models that get blown away when the business changes. ... If your business is currently too chaotic to support a complex model, don't build one."